AR headsets with improved pinhole mirror arrays

ABSTRACT

Augmented reality headsets. A plurality of tilted pin-mirrors imbedded between an inner surface and an outer surface of a combiner, where the plurality of tilted pin-mirrors are configured to reflect the guided image light towards the eye box, and wherein the plurality of pin-mirrors include one or more gaps between them wherein the one or more gaps allow the passage of an ambient light through the combiner towards the eye box.

BACKGROUND

As computer technology is migrating in sophistication, complexity, powerand realism, one could say that the ultimate goal is to create acomputerized human being. As this process is unfolding before our eyes,the humans are not sitting idly by just watching, but rather, they arealso taking steps toward entering a computerized world. We have seenthis in the distance past with the creation of the Six Million DollarMan as well as the migration of Sci-Fi movies like the Matrix and ReadyPlayer One. Maybe someday we will live in a world where the computer andmankind are fully joined, but in the meantime, the human venture intothe computer world is being played out in the virtual reality andaugmented reality technologies.

Virtual reality (VR) is an interactive computer-generated experiencetaking place within a simulated environment. This simulate environmentoften include audio and visual elements, as well as other elements suchas sensory feedback (vibrations, motion, smells, temperature and touch(haptics)). The VR immersive environment can be similar to the realworld or it can be fantastical, creating an experience that is notpossible in ordinary physical reality.

Augmented reality (AR) systems may also be considered a form of VR. Themain different between AR and VR is that AR that layers virtualinformation over a live camera feed or actual visualization of one'senvironment with the eye giving the user the ability to viewthree-dimensional images integrated into his or her real world.

At present, there are two primary architectures for implementing ARglasses. In a first version, image light is incident to the inside faceof a curved combiner, and then redirected towards the eye box. In orderto provide nominally collimated image light to the viewer for all fieldpoints, the combiner can have an extreme shape, particularly if a largefield of view (FOV) is sought. In such systems, it can also be difficultto fit the optics on the temples, next to the head, while having theimage light rays steer clear or miss hitting the side of the face. In asecond version, such as the MICROSOFT HOLOLENS, the image light isdirected into an edge of a flat waveguide or light guide, through whichit propagates, until it is extracted or redirected by output couplingoptics towards a viewer's eyes. Use of such waveguides canadvantageously reduce the volume needed for the optics, but thediffraction gratings used for light coupling can create both chromaticand stray light image artifacts. Also, at present, the migration to ARis plagued with limitations, including the cost of the equipment, thesize, bulkiness or weight of the equipment, and the limitedfunctionality of the equipment.

Another problem that is particularly evident in AR is that with thereal-world images combined with the virtual images, a user may havetrouble focusing. From an optical perspective, everyday objects are amyriad of points of light-emitting rays that, after penetrating thepupil of the eye, form an image on the retina. According to the laws ofgeometrical optics, when the optical system of the eye is well focused,each point of light in the object forms a point of light in the retinalimage. In reality, the image is not a simple point, because the physicalfactors of diffraction and interference distribute the light across theretina.¹ ¹Larry N Thibos, Cameron A Thibos US Ophthalmic Review, 2011;4(2):104-6 DOI: http://doi.org/10.17925/USOR.2011.04.02.104

FIG. 1 depicts optical and imaging effects of pinhole glasses. When theoptical system of an eye 100 is mis-focused on an object 115, the imageof any single point of light is uniformly spread out across a small areaof retinal surface. As illustrated in FIG. 1, the shape of the pupil 110of the eye 100 determines the shape of the blurred retinal image. Giventhat the shape of the pupil 110 in the normal human eye 100 is circular,the image is a circular region called a ‘blur circle’ 120 or ‘blurdisk’. By comparison, the eye of a cat has a vertically elongated pupil,so the retinal image would be a ‘blur ellipse’. The human pupil alsotakes on an elliptical appearance when viewed from the side, so theblurred image in peripheral retina is also a ‘blur ellipse’. Someanimals have a pupil that forms two small pinholes, which would producea pair of small blur disks for every object point, a natural example ofmonocular diplopia.² ²IBID

Pinhole glasses, also called stenopeic glasses, are eyeglasses withlenses that consist of many tiny holes filling an opaque sheet ofplastic. These “pinholes” block indirect rays from entering the eye,thus preventing them from distorting your vision. While this does notactually improve the focusing ability of the eye, it does reduce thesize of the blur circle on the back of the retina, so reasonably clearvision may be achieved.³ However, while viewing through a single pinholecan improve resolution, within the trade-off of aberration blur versusdiffraction blur, the resulting image will be dim. By comparison,stenopeic glasses with multiple pinholes increase the vision angle andthe amount of light that reaches the retina. If two pinholes areseparated by less than the diameter of the pupil aperture, two pencilsof ray coming from one light point pass through the pupil and form twonearby retinal images. Optimization is necessary, as using too large ofa separation will result in dead spots in the field, while too small ofa separation will produce multiple images. ³Using Pinhole Glasses forVision Improvement,https://www.verywellhealth.com/do-pinhole-glasses-work-3421901 By TroyBedinghaus, OD Updated Oct. 8, 2017

Thus, there are yet opportunities for improved wide FOV AR glasses orheadsets that have better optical designs and performance, includingapproaches that provide enhanced resolution or smaller blur circles.

SUMMARY

The present disclosure is related to augmented reality headsets and moreparticularly light guided augmented reality (AR) display that include animage source and imaging optics. The imaging options provide an imagelight. The AR display also includes a combiner into which the imagelight is end or edge coupled, and from which the image light is guidedand output towards an eye box. A plurality of tilted pin-mirrorsimbedded between an inner surface and an outer surface of the combiner,where the plurality of tilted pin-mirrors are configured to reflect theguided image light towards the eye box, and wherein the plurality ofpin-mirrors include one or more gaps between them wherein the one ormore gaps allow the passage of an ambient light through the combinertowards the eye box. With respect to the image light, the tiltedpin-mirrors appear to form a high fill factor array, whilesimultaneously appearing as a low fill factor array for ambient lightincident to an outer side surface of the combiner. These and otherembodiments, features, aspects and benefits are described more fully inthe detailed description with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts optical and imaging effects of pinhole glasses.

FIG. 2 depicts the concept of virtual images.

FIG. 3A depicts an exemplary projection type AR headset.

FIG. 3B depicts an exemplary light guide type AR headset.

FIG. 4A depicts a concept for pin mirror arrays for use in AR headsets.

FIG. 4B depicts a concept for pin mirror arrays for use in AR headsetsin a stacked configuration.

FIG. 5A depicts a second concept for pin mirror arrays for use in ARheadsets.

FIG. 5B presents a cross-sectional view of the pin mirror array of FIG.5A taken line 5B-5B.

FIG. 6A depicts a potential orientation of the pin-mirrors in apin-mirror array.

FIG. 6B depicts a potential orientation of the pin-mirrors in apin-mirror array.

FIG. 7A depicts side view of portions of an improved light-guide type ARheadset, including image light propagation through a combiner or eyepiece with a pin-mirror array.

FIG. 7B depicts a side view of the embodiment of FIG. 7A with moredetail showing the slice edges.

FIG. 7C depicts top side view of portions of an improved light-guidetype AR headset of FIG. 7A.

FIG. 7D depicts top front view of portions of an improved light-guidetype AR headset of FIG. 7A.

FIG. 8 depicts a cross-sectional view of the pin-mirrors within acombiner, to illustrate a spatial variation of the pin-mirror tilt.

FIG. 9A depicts a second improved approach for a pin-mirror based lightguide AR headset having a dual light guide and a curved reflector.

FIG. 9B is a side elevational view of the pin-mirror based light guideAR headset of FIG. 9A.

FIG. 9C is a perspective view of the pin-mirror based light guide ARheadset of FIG. 9A with the pin-mirrors in a different configuration.

FIG. 9D is a top-pan view of the pin-mirror based light guide AR headsetof FIG. 9A with the pin-mirrors in a different configuration.

FIG. 9E is a perspective view of the pin-mirror based light guide ARheadset of FIG. 9A with light paths illustrated.

FIG. 10A depicts a viewer's eye receiving virtual image light from partof an AR headset having pin-mirrors.

FIG. 10B depicts a viewer's eye receiving virtual image light from partof an AR headset having pin-mirrors.

FIG. 10C depicts a viewer's eye receiving virtual image light from partof an AR headset having pin-mirrors.

FIG. 11 is a flow chart illustrating an exemplary optimization methodfor designing combiners or eyepieces for AR headsets having a pluralityof pin-mirrors.

FIG. 12 depicts another improved AR headset, of the projection type,having a plurality of pin-mirrors.

FIG. 13 depicts aspects of the construction of a combiner having aplurality of pin-mirrors.

FIG. 14 depicts a fourth improved AR headset, of the light-guide type,having a scanning image light source and a plurality of pin-mirrors.

FIG. 15 depicts a portion of a pixelated tri-linear image source for usein providing a scanning image light source.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present invention, as well as features and aspects thereof, isdirected towards providing an optical solution that utilizes pin-holetechnology to reduce the blur circle for AR solutions, such as ARHeadsets (ARHS).

A virtual image is an image that from the user's perspective, is notprojected on a screen but rather appears to be present in space. Thus,in an AR system, virtual images are generated to give the appearance ofexisting in the user's real-world space.

A good tutorial of this field of art can be found in United Statespublished patent application US20100290127A1, which is summarized in thenext few paragraphs.

A virtual image is different from a real image and the images are formeddifferently as well. A real image is an actual image that can beobserved directly by the unaided human eye. A real image is present inthe real world and the image is perceived by the human eye when lightbouncing off of the image enters into the eye through the pupil andlands on the retina wall within the eye. Thus, a real image is aperception of a physically existing object at a given location. Anexample of a real image is a photograph. Real images can be createdelectronically with devices such as cathode ray tubes (CRT), liquidcrystal displays (LCD) screens, liquid crystal on silicon (LCOS)devices, digital micro-mirror display devices (DLP or DMDs), lasers,super luminescent diodes (SLEDs), and organic light emitting diode(OLED) displays. The OLED is an example of an electronic display thatprovides a real image. The size of the display surface limits the sizeof the real image that can be provided to the observer.

Virtual image displays provide an image that is not observable on aphysically existing viewing surface or in a tangible world. The virtualimage is formed at a location in space where no display surface exists.An example of creating a virtual image is when someone looks at smallitems through a magnifying glass. The magnifying glass makes the imageappear larger and the image also appears to be located substantiallybehind the surface where the item actually exists. Thus, while the itemis a real image, the magnification of the item is a virtual image. Bydefinition, a virtual image can exist at a location where no displaysurface exists. The size of the virtual image therefore is not limitedby the size of a display surface. Virtual image electronic displays thushave the advantage of eliminating the need for a large display surfacein order to produce a large electronic image.

FIG. 2 depicts the concept of virtual images. Further, FIG. 2illustrates how a virtual image can be created by viewing an object 202through a magnifying lens 204. The object 202 is placed within the focallength 210, or f of a magnifying lens 204. The virtual image 206 that isformed appears to the viewer at point 208 and is enlarged and has thesame orientation as the source object 202. As a result of this type ofimage formation, the size of the virtual image 206, as perceived by theviewer 212, is limited by the magnification of the display system asopposed to the size of the electronic display. This enables virtualimage displays to be designed that provide the same amount ofinformation per screen as real image displays, yet occupy a smallerspace.

Thus, it can be appreciated that an optical system is used to create avirtual image. As such, the eye and the viewing surface properties of areal image are the factors that determine the viewing parameters,whereas in a virtual image display, the optical system determines mostof the viewing parameters.

In the creation of an AR environment, especially one that is createdthrough the use of a viewing headset, light waves enter the pupil of theeye from the real environment as well as from the virtual imagegenerating optic system. In an AR headset (ARHS), a real image thatserves as the source object is first formed by an imaging component thatis electronically energizable to form an image from image data. Inembodiments of the present invention, an OLED or other emissive displaydevice is utilized to create a real image and then, a virtual image isthen created through an optical system. Obviously, within an ARHS, theimaging source needs to be small and inexpensive in order to reduce thesize and overall cost of the ARHS. But it should be understood thatwhile OLEDs can be utilized, other image sources may also be utilized,such as LCDs, etc. The optic system then forms a virtual image of thereal image generated by the source, or OLED in the describedembodiments. The virtual image is then seen by the viewer along with theactual real world in which they are located.

FIG. 3A depicts an exemplary projection type AR headset. FIG. 3B depictsan exemplary light guide type AR headset. FIG. 3A depicts a portion ofan exemplary projection type Augmented Reality headset 300, in whichincident light reflects off the inner or inside surface of a combiner,towards a viewer's eye. This ARHS display includes a frame 302 with aright arm or temple 304 and a strap 306 that can be used to secure theARHS 300 to a user's head. A comparable system (not shown) is typicallyprovided for the left eye. Depending on the weight of the ARHS, thestrap 306 that extends over the top of the head and/or behind the neckmay or may not be needed to provide additional support. The headsetrests on a viewer's nose with enough offset, or eye relief, of thecombiners from the viewer's eyes so as to be comfortable.

In particular, as shown in FIG. 3A, a projection type ARHS can includevirtual image generating optics 310 on the right temple 304. The imagegenerating optics 310 can include a LED display 312, imaging optics 314,and a variable opacity combiner 316, that together provide and directvisible AR image light to a viewer's eye. In particular, the image lightprovided by the image generating optics that is directed towards thevisor or combiner 316, hits the inner surface 318 of the combiner,between a temple 304 and the nose bridge 305, and reflects back towardsthe user's eye, or a target area or eye box 320 nominally overlappingwith the expected eye position. An eye box is defined as the volume ofspace within which an effectively viewable image is formed by the ARHSdisplay, and it represents a combination of an exit pupil size and aneye relief distance. Nominally, the exit pupil size is assumed to bethat of human viewer's experiencing photopic light levels (e.g., ≥1.0cd/m²). Whereas, an eye relief is the distance from the last surface ofan eyepiece within which the viewer's eye can obtain the full viewingangle. The visor or combiner 316 is curved and shaped to fit well, orconform to, the shape or contours of a viewer's face.

A second set of image generating optics (not shown in FIG. 3A) likewisecan provide image light to a viewer's left eye. The combiner 316, oreyepiece, is referred to as having a variable opacity in part as theamount of ARHS image light that is seen by a viewer depends on thereflectivity of the dichroic coating provided on the inner surface 318of the combiners 316, while the transmissivity of the combiners alsohelps determine the amount of ambient or environmental light thatreaches a viewer's eyes and the amount of ARHS image light that is lostthrough the glasses into the ambient environment. Nominally, thedichroic coatings of the combiner are nominally 50% reflective for thevisible spectrum, but the reflectivity or transmissivity of thecombiners 316 can also vary spatially and angularly over the surface ofthe combiners.

A typical ARHS 300, such as the MICROSOFT HOLOLENS, can provide imagecontent to a limited FOV per eye of <50°. Ideally, for some viewingapplications, a projection type ARHS 300 would support a WFOV per eye inexcess of 90°, to as much as 115° or larger, and thus provide content tothe user's peripheral vision. In projection type ARHS glasses, the imagegenerating optics 310 would produce a fan of rays that spans anasymmetrical FOV ≥30° in total width, that then intersects with a highlycurved combiner (e.g., radius ≥60 mm) having a compound or complex(e.g., aspheric) curvature, to produce nominally “collimated” ray fansdirected over a large FOV to an eye box 320 of ≥10 mm in width. Thistype of ARHS can be difficult to design and make because of the space,weight, and image quality constraints, as well as the difficult designand fabrication specifications for the optics.

FIG. 3B depicts another exemplary type of AR headset 350. In this case,image light from virtual image generating optics 360 is directed into aninput coupler 362 and into a wave guide or light guide 364. The imagelight can then exit towards a viewer's eye via an output coupler 366.The input coupler, which is positioned at or near an end of the lightguide, can be a prism, diffraction grating, or edge-lighting mechanism.The light guide for an optical waveguide display is a sheet oftransparent material with two surfaces, which are locally parallel andoptically polished.

In this ARHS display, the coupled wave or image light is confined insidethe waveguide or light guide through total internal reflection (TIR) onthe waveguide surfaces and propagates along following a zigzag TIR lightpath 368. As shown in FIG. 3B, the projection or image generating optics360, and pre-input coupler 362 edge couple “collimated” image light intothe plane of the light guide, and convergent focused image light in theplane vertical to the light guide. In the latter case, the image lightcan be convergent at ˜F/4, at a distance just inside (from the inputcoupler) the waveguide of about 23 mm, with a tilt beyond the criticaldegree, such as ˜70 degrees from the surface normals. The image lightcan then TIR its way through the light guide(s) to the diffractiongrating output coupler(s). A hologram or diffraction grating is placedparallel to and immediately in contact with the waveguide. When thegrating is illuminated with the guided wave, the image light is directedto a viewer's eye, enabling the viewer to see a virtual image.

In one version, the complete FIG. 3B system has three light guidesarranged in parallel; one per color (RGB). Similar systems, with one orthree waveguides, can be used to provide image light to a viewer's othereye. As compared to the ARHS 300 of FIG. 3A in which image light isdirected onto the highly curved inner surface 318 of the combiner 316,the use of waveguides can enable a smaller ARHS 350 with simpler imagingoptics. The MICROSOFT HOLOLENS glasses are one commercially availableexample of this type of glasses.

However, projecting image light in and out of this light guided systemintroduces its own set of problems, particularly with regards to the“diffraction gratings”. As the waveguides are heavily wavelengthdependent, this type of glasses is typically made with three separatewaveguides with three separate sets of gratings to handle each of theRGB colors. This separation, along with their display system, can leadto a user seeing the virtual images separated into their colorcomponents. Another side effect for the lightguide type of ARHS, is thatwhen a viewer's head is moving, a white spot (combined by R+G+B) can beseen as separated into three separated RGB spots. A further side effectis that when a user is directly viewing a bright light source from theambient real environment, the diffraction grating can cause some ghostimages. Also, the gratings can also redirect and disperse stray ambientlight and create additional artifacts, not related to either thedisplayed virtual image or the real scene.

FIG. 4A depicts a concept for pin mirror arrays for use in AR headsets.FIG. 4B depicts a concept for pin mirror arrays for use in AR headsetsin a stacked configuration. A variety of improved AR headsets usingnovel pin-mirror based combiners, which are also referred to aseyepieces or visors, are disclosed. According to an embodiment of thepresent invention, as shown in FIG. 4A, a novel type of improved lightguide combiner 405 can be made of adjacent or interlocking slices 410 oftransparent glass or polymer, with at least one row or one dimensional(1D) array or linear array of reflective surfaces or pin-mirrors 430 toform part of a pin-mirror array 435 that are fabricated along tiltededge faces or facets 425 of a slice 410. The nominally preferred facettilt angle Ø 412 is 45° relative the flat sides 411 of the slices 410 asa non-limiting example but it is appreciated that other angles may alsobe utilized. A series of pre-fabricated slices 410 can then be assembledalong the x-axis to form a larger flat combiner 406 providing atwo-dimensional (2D) pin-mirror array of imbedded tilted reflectors(pin-mirrors 430). The individual small mirror areas in FIG. 4B, whichare positioned relative to another by a center to center pitch 432′ and432″ (collectively referred to as 432), or are separated from each otherby edge to edge gaps, can be optimized to be spaced with nominally thesame or different pitch or gaps in the horizontal and verticaldirections. Although the pitch 432′ and 432″ varies by design, and canvary spatially within a design, the pitch 432′ and 432″ can be equal ordifferent, and is most commonly is in 4-6 mm range. The pin-mirrors 430are reflectors, which can be provided with a metal coating, such as ofaluminum or silver, or as a multi-layer dielectric or dichroic thin filmcoating, and for example, provide ˜80-96% local reflectivity, dependingon the coating type. Although the pin-mirrors 430 are nominallyfabricated with broadband visible reflective coatings, notch typedichroic coatings, that reflect a set of narrow (e.g., ≤25 nm wide) RGBspectral bands can also be used. As these notch type coatings can allowambient light outside of the narrow reflection bands to pass through thepin-mirrors to the eye box, the optimization of the efficiency of theambient light transmission can be desensitized relative to theoptimization of the size and spatial density of the pin-mirrors 430.

Considering FIG. 4A and FIG. 4B in greater detail, the combiner 405 canbe made with interlocking slices 410 of glass or plastic, whose tiltededge facets 425 are coated partially or completely using materials toprovide a partially transparent or completely reflective surface. Themirrored facets can then be coated with an index-matching adhesive, andstacked sequentially to form a larger combiner 406, for which thenon-mirrored surfaces form uniform, optically-continuous segments. Forgreater mechanical stability, the slices 410 can also be assembled ontoa larger substrate 440, which can be provided on either side of thecombiner 406, towards or away from the viewer's eyes. Once a combiner isassembled with imbedded micro-mirrors or pin-mirrors 430, the outersurfaces of the combiner 406 can also be fabricated with anti-reflection(AR) coatings or other coatings to improve the optical quality of theassembly.

As another example, an improved combiner with pin-mirrors 430 can befabricated by cutting a row of grooves partially into a substratematerial to provide the tilted edge facets 425. The pin-mirrors 430 ormicro-mirrors can then be deposited or coated in either a linear or 2Darray within the grooved facets 425. To imbed the pin-mirrors 430, thegrooves can then be filled with an inserted compensating piece ofsubstrate material, or with adhesive, or with a 3D printed volume ofindex matched material. Alternately, a second substrate with matchingprotruding faceted ridges can be overlaid on the first substrate, so theridges fill the faceted grooves. The two substrates can be fusedtogether, or attached by adhesive, or a second equivalent substrate canbe cast or molded over the first one. As a further alternative, thereflective coatings for the pin-mirrors 430 or micro-mirrors can bedeposited or formed on protruding ridges provided on a substrate, and asecond grooved substrate, or a set of slices, can be used to fill in thespaces between the ridges, and to create an overall combiner 405 withsmooth external surfaces (inner surface 427 and outer surface 428).

FIG. 5A depicts a second concept for pin mirror arrays for use in ARheadsets. FIG. 5B presents a cross-sectional view of the pin mirrorarray of FIG. 5A taken line 5B-5B. As such, an alternate configurationfor the improved combiner is depicted in FIG. 5A and FIG. 5B, in whichmultiple rows of tilted reflectors or pin-mirrors 530 are fabricated ona tilted facet 525 of a slice 510 to form part of a pin-mirror array537. Multiple such slices can then be assembled into part of a largercombiner 505 providing a larger 3D pin-mirror array 537 of tiltedpin-mirror sub-arrays 535 of pin-mirrors 530 are provided on an imbeddedsurface within a combiner 505405. While FIG. 5A and FIG. 5B depict thistype of combiner or eyepiece before the slices and sub-arrays areassembled into the combiner, FIG. 14 depicts an improved ARHS (1400)with an assembled combiner of this type, including a pitch 1432 betweensub-arrays. A variety of related parameters, including the extent of thesub-arrays 535, the pitch 532 between the pin-mirros, the gaps 540 andgaps 545 between the pin-mirrors, the parallelism or relative skew ortilt between the sub-arrays, the curvature of the sub-arrays, and thepin-mirror patterning within or between the individual sub-arrays(including in-plane offsets), can be optimized. For example, thepin-mirror pitch or a pin-mirror sub-array positioning or offset can bevaried spatially from one sub-array to the next, so as to optimize theapparent fill-factor for the transiting image light.

FIG. 6A depicts a potential orientation of the pin-mirrors in apin-mirror array. FIG. 6B depicts a potential orientation of thepin-mirrors in a pin-mirror array. Also, as presented in example inFIGS. 6A and 6B, the orientation of the rows of pin-mirrors 630A canseem to be in a row, or a tilted row 630B depending on how the assembledpart is viewed. This is made clearer in FIG. 7(A-D), where an improvedlight guide type AR headset 700 is shown in cross-section, and both theside and end views of a combiner 705 are depicted along withillustrations of propagating image rays. As shown in FIG. 7(A-D), asseen from the inner or outer surface, an assembled combiner 705 lookslike a nominally transparent member with a 2D array of pin-mirrors 730.Whereas, as seen best in the side view, the assembled combiner lookslike a narrow structure with imbedded angled mirrors 730. When acombiner 705 is assembled using these slices, the overall combinerstructure can provide several “columns” of reflectors, as long as therows or columns don't block each other (see FIG. 6B). This is incontrast to the left image (FIG. 6A), where the pin-mirrors 630 couldblock each other, in terms of the paths to an eye box 720. As seen onFIGS. 6A and 6B, the number of pin mirror layers along x-z plane isdependent on the thickness of the eyepiece. Two or three layers can bepreferentially selected if the nominal diameter of the pin mirror isoptimized to be 2 mm, as a non-limiting example.

FIG. 7A is a top-planar view of an ARHS visor 700 that with a pin-mirrorbased combiner 705 and virtual image generating optics 750, can beincorporated into an improved AR headset display. The visor 700 receiveslight rays 760 from the real-world environment as well as light rays 745from a virtual image source 750. The virtual image generating optics 750can include an LED or OLED array with a 2D array of light emittingpixels that can emit light in the F/1.5-F/2.5 range. These optics canfurther include spherical or cylindrical optical elements (e.g., lenses780 or mirrors) to modify the divergent image light, and nominallycollimate this light from a given pixel in at least one direction, andto then direct the light into a visor or lightguide (see FIGS. 9A-E forfurther illustration of lens elements 780). The visor 700 includes aseries of embedded mirrors or pin mirrors 730 that are embedded betweenan external inner surface 727 and an external outer surface 728 of thevisor 700. The beam from each pixel on the image source is nominallycollimated by the projection optics and then coupled into the lightguideeyepiece (705), after which is reflected by the embedded mirrors or pinmirrors 730 and coupled out towards an eye box 722 to be visualized by ahuman eye. As image light from a display pixel interacts with one ormore pin-mirrors 730, and light from other display pixels interacts withother pin-mirrors, an aggregate light beam can be directed to the eyebox 720. The aggregate light forms a convergent light cone directed toan eye box 720, but image light for any one image pixel is nominallycollimated into the eye box. The optics of a viewer's eye can then alteror focus this light so that an image can be perceived. The apparentfield of view depends on the angular width of the aggregate cone oflight directed into the eye box 720. Although FIG. 7A does not showdetails of light coupling into the light guide combiner, the preferredtechniques are edge coupling, a coupling prism (as in FIG. 4), or usingan edge facet (FIGS. 9A-E).

In this display device, image light rays 745 can be coupled into an edgeof an improved light guide combiner 705, or eyepiece, from one or morespecified input facets or input couplers, and after propagating througha light guide portion 720 of the combiner 705, be reflected by theimbedded pin-mirrors 730 and projected outward towards a viewer's eye.Depending on the directionality of the incoming image light,corresponding to a given image pixel, the light will propagate a shorteror longer distance along the length of the light guide, beforeinteracting with one or more pin-mirrors 730. As shown in FIG. 7A, thelight can be directed through the light guide in part by total internalreflection (TIR). FIG. 7A depicts the image light as bouncing once andreaching a target pin-mirror 730, but TIR provides that the light istrapped and can bounce multiple times within a flat light guide portionof the combiner, and likely will do so, around or past part of the arrayof pin-mirrors before reaching its target pin-mirror(s) 730.

With respect to FIG. 7A, the pin-mirrors 730 are nominally sized to havea real sub-pupil ˜0.3-2 mm full width, as compared to the nominalphotopically adapted adult maximum pupil width of ˜4 mm. A goal is thatthe individual pin-mirrors 730 are too small for viewers to really seeor focus on while the AR glasses are being worn. Also, while thepin-mirrors 730 can be rectangular in shape, as suggested in FIGS. 4A-B,the pin-mirrors 730 are preferentially fabricated to be circular orelliptical in shape, as depicted in FIG. 7C-D. Then, taking the nominal45-degree tilt of the imbedded facets 725 into account, the nominallyflat pin-mirrors can have apparent sizes that can be as small as ½ thereal size, and a goal is to have the pin-mirrors 730 appear circular toa viewer's eye. Thus, pin-mirrors 730 having a real elliptical shape, asshown in FIG. 7D, can have a circular appearance with respect to aviewer when tilted. The pin-mirror shape can also be more irregular.

As also shown in FIG. 7D, the pin-mirrors 430 are offset from one toanother by fairly large gaps within a pin-mirror array 735, that in thedirection of light propagation can be as large as 6-10 mm wide, or about3-5× the width of the pin-mirrors 730. By comparison, for theorientation of the combiner that is orthogonal to the direction of raypropagation, the real gaps can again be about 7-10 mm wide, but as seenfrom direction of the virtual imaging generating optics 750, thestaggered pin-mirror-arrays 735 appear to have little to no apparentgaps. However, from the viewpoint of the ambient light, the gaps betweenthe pin-mirror arrays 735 are sized to allow a significant portion ofambient light rays 760 through the glasses so as to enable an AR viewingexperience.

In use, image light rays 745 emanating from a given image pixel of theimage generating optics 750 experience or interact or reflect off atleast one pin-mirror 730 and preferably several, but each pin-mirror 730re-directs light for a multitude of pixels towards the eye box 722.Depending on the design of the combiner 705 and the AR headset 700, apin-mirror array 735 within a combiner 705 can have a total pin-mirrorarray size of 20-30 pin-mirrors 730 per eye, and maybe as many as 100total pin-mirrors 730. The pin-mirror array size can also be expressedas the total area (see FIG. 7D) of a combiner that includes pin-mirrors,which can for example span a 50 mm width and 40 mm height. Also, sincethe size of the pin mirrors 730 are rather small, the transparency ofthe glasses for ambient light can be maintained as well. However, ascompared to the conventional AR headset of FIG. 3B with diffractiongrating light output couplers, which have optical features on themicrometer or nanometer scale, these pin-mirrors are relatively large(millimeter scale) and do not cause significant diffractive effects.Image light reflected by the pin-mirrors 730 will be directed to aviewer's eye, while ambient light rays 760 from the broader environmentthat the viewer resides in, can transit the gaps between thepin-mirrors, to reach a viewer's eyes. The image light directed by thecombiner 705 towards the eye box 722 to produce a virtual image, as seenby a viewer, for any given image pixel, is meant to be “collimated” witha target vergence of 0.0 deg.±˜20 arcmin. As a result, the viewer canhave an augmented reality (AR) or mixed reality (MR) viewing experience.

A benefit of this approach is that with controlled fabrication andplacement of the pin-mirrors 730, deflection of image light towards aviewer can be optimized, largely independent of the further optimizationof the combiner 705 for allowing transit of ambient or environmentallight to a viewer. In particular, by fabricating a combiner 705 with lowarea-density, but highly reflective imbedded or internal mirrorsurfaces, whose reflectivity is independent of the inner and outercombiner surfaces, can enable a substantially transparent lens, with thesame effective reflection as the typical partially reflectivesingle-surface combiner.

Considering FIG. 7A, the efficiency of directing virtual image lighttowards a viewer's eye largely depends on the reflectivity (e.g., R˜92%)of the pin-mirrors 730, and the apparent high fill factor of both thepin-mirrors 730 and the pin-mirror arrays 735, as seen or experienced bythe incoming virtual image light. As seen by the incoming virtual imagelight, the circular or elliptical pin-mirrors have a fill factor of˜80%, as compared to being square or rectangular mirrors. The apparentfill factor from one pin-mirror array 735 to another, as experienced bythe image light, will depend on the optimized array positioning,manufacturing tolerances, and the stability or robustness of the productthereafter. Assuming an apparent array fill factor of ˜92%, and notincluding optical absorption of the slices or substrate, and Fresnellosses or AR coatings at the surfaces, the overall optical efficiency ofthe pin-mirror array can be estimated as ˜0.92*0.8*0.92≈0.68, which canbe a significant improvement over existing ARHS light guides. Bycomparison, with respect to the incident ambient light, the pin-mirrors730 are sparsely located and small, and the apparent fill factor is low(e.g., ≤20%, and preferably ≤10%). Therefore, the pin-mirrors 730 andpin-mirror arrays 735 can be optimized within a combiner 705 and a lightguide based ARHS, to improve both image quality and a light efficiencyor high fill factor for the virtual image light (745), with littleimpact on a high light efficiency or low fill factor for the ambientlight (760). Other efficiency optimizations, including for nominallyequal ambient and image light through the pin-mirror array efficiencies(e.g., ˜75% each), or for image light efficiency being higher thanambient light efficiency, can be favored, depending on the application.

The improved combiners 705, with pin-mirrors 730 also can provide someof the benefits of pin-hole glasses, for a user viewing the projectedvirtual image content. As previously discussed, pin-hole technologyreduces the blur circle by filtering out some of the light waves. Thisis similar to the effect that is realized when a person squints theireyes to improve vision. Squinting reduces the size of the de-focus lightrays that land on the retina. Pinhole glasses include a series of smallholes within an opaque visor that allows only a portion of the light topass through and enter the pupil of the eye. The pin-mirrors 730 canhave an analogous effect for viewing of the virtual image content. Theeffective size of the pin-mirrors 730 is increased by the pinhole opticseffect, which both increases the depth of field and provides a wide eyebox. The apparent resolution that can be achieved by a pin-mirror 730with a diameter of D, is roughly 1.97/D arc minutes.

In the case of the AR headset 700 of FIG. 7A-D, the image generatingoptics 750 and associated input coupler optics 755 can be located to theleft or right or the viewer's eyes, near the temples, with the imagerand associated optics positioned along the side of the viewer's head.Alternately, the input coupler and imager and associated optics can belocated above the viewer's eyes, near the forehead, so that image lightis coupled into the combiner at or near the upper edge. In this case, asshown in FIG. 8, each of the imbedded pin-mirrors 830 are generallyoriented with a vertical tilt to direct the image light towards an eye.

Aspects of the fabrication of the combiners were previously discussedwith respect to FIGS. 4-7. In greater detail, it should be understoodthat the inner surface and outer surface (i.e. respectively 727 and 728in FIG. 7A), to provide a functional light guide, whether fabricatedwith or without a substrate (i.e. substrate 440 in FIG. 4A, should benominally parallel. In the preferred design, the assembled light guideor combiner or eyepiece is flat, with only modest wedge (e.g., ≤0.1°.Also, the spatial flatness of the individual outer surfaces (i.e. 727and 728 respectively in FIG. 7A) of the light guide eyepiece orlightguide visor should be flat to roughly λ/4, which is 138 nm, for awavelength of 550 nm. A preferred thickness tolerance for exemplarylight guide combiners is ˜±0.20 mm. A 60-40 surface quality would betolerable. If a substrate is included, it should nominally be made withthe same material, whether glass or plastic, as the slices in thevarious embodiments. The exemplary visors can also be fabricated with anouter frame (not shown), similar as to that for a pair of eyeglasses, tohelp hold the slices together.

The various exemplary improved light guide combiners can also befabricated by casting or injection molding, for a relatively low cost.By comparison, a typical waveguide combiner with diffraction gratinglight couplers has a coating or texture on one or both of the inner andouter combiner surfaces, to create a partially reflective element, butthese coatings or textures also reduce the transparency of the element.This results in a tradeoff between transparency and reflectivity, andnever quite fulfills either requirement.

In an exemplary embodiment, the structure of a combiner or visor can beattached by fusing or joining two or more slices together with a mirrormesh sandwiched between them. In another embodiment, this may beachieved by creating small holes penetrating the surface of the visor toa particular depth, and then depositing mirrors within the holes. As anon-limiting example, gallium could be injected into the holes in aliquid state and once solidified, they could be used as mirrors. Itshould be appreciated that these are simply exemplary techniques thatcan be used to create embodiments of the visor or combiner and shouldnot be construed as a limitation.

It should be appreciated that while FIGS. 4A-7D may seem to suggest thatthe individual micro-mirrors and rows or linear arrays of micro-mirrorsare fabricated across a combiner on parallel planes of planar edgefacets, that those skilled in the art will understand, as depicted inFIG. 8, that the combiner 805 can provide a spatially variant tilt ofthe pin-mirrors 830 or pin-mirror arrays 835 across the combiner 805.Relative to the light input edge or input light coupler, and the innerand outer surfaces of the combiner 805, the mirror facets 825 can betilted at spatially variant angles across the light propagation lengthof the combiner. For example, near the virtual image light input end ofthe combiner 805, the pin-mirrors 830 can be tilted at a nominal angleof Ø1 (i.e. 47° as a non-limiting example), while in the center regionof the combiner 805, nearest the eye box 820, the pin-mirrors can betilted at the nominal angle of Ø2 (i.e., 45° as a non-limiting example),and at the far end of the combiner 805, furthest from the input end, thepin-mirrors can be tilted at the nominal angle of Ø3 (i.e., 43° as anon-limiting example). An optimization with a spatial tilt variation ofthe pin-mirrors 830 provides an additional degree of design freedom thatcan ease the optical design of the imaging optics, or the combinerdesign and fabrication specifications. Also, if the improved ARHS 800has an eyepiece or combiner with tilted pin-mirrors (FIG. 8) or tiltedpin-mirror arrays (see FIG. 5A, 5B and FIG. 14), and the pin-mirrorcoatings are reflective dichroic notch coatings, than the pin-mirrortilt or combiner curvature can help compensate for the spectral shiftsthat occur when dichroic coatings are tilted. Alternately, the notchposition of the dichroic coatings can be deposited to vary spatiallyacross the combiner so that the apparent notch spectral position to theeye box appears constant. The widths of the pitch 832, or of the gapsbetween the pin-mirrors 830, can also be optimized spatially across acombiner 805 (e.g., optimizing the spatial frequencies). Although thesize, shape, and tilt of the actual pin-mirrors 830 can be optimized tovary spatially across a combiner, a goal can be that the apparentpinhole size, as seen by a viewer, is nominally constant (e.g., within±15% of average) across the combiner. The optimization of theseparameters can also benefit optical efficiency, in terms of how muchvirtual content image light can be reflected towards the eye box, andthus also the potential sizes of the pin-mirrors. For example, ifspatial tilt optimization allows smaller mirrors, then transmission ortransparency for ambient light can be increased. Also, the size andpositioning of the eye box 822 can be improved with spatial optimizationof the pin-mirrors 830, to either side and to the top and bottom. Thepreferred range for the size of the eye box 822 is 10-15 mm.

Additionally, in any of the embodiments but described with regards tothe embodiment in FIG. 8, the imbedded edge facets 825 on which thepin-mirrors 830 are fabricated, and indeed the entire combiner 805, canalso be fabricated to have a curvature, which can be concave or convex,and symmetrical or asymmetrical (e.g., cylindrical). For example, theentire light guide or combiner 805 can have a curvature, or compoundcurvature, oriented inwards towards the eye. Thus, the facets 825 of theslices 810 upon which the pin-mirrors were fabricated can also havecurvature. Alternately, the combiner 805 or light guide can be a flatdevice with nominally plane parallel surfaces, but one or more facets825 upon which the reflective mirror coatings are fabricated, can befabricated with a curvature, resulting in a curvature for a pin-mirrorarray 835. The individual pin-mirrors 830 can also have a localizedcurvature or scalloping on a facet 825 that either is otherwisenominally flat or which has its own curvature with a much larger radius.Curving the individual pin-mirrors 830 or the facets 825 can provideadditional design freedom for the entire optical design, including thatof the image generating optics 850. For example, a large radius ofcurvature (e.g., ≥150 mm), or small optical power, that is eitherconcave or convex, can be used. The pin-mirrors 830 can also have aspatially variant curvature, for example where the pin-mirrors 830proximate to the eye box 822 are flat, and the pin-mirrors 830 nearestthe sides or edges can be optimized with curvature. Curvature of thepin-mirrors 830 can be useful to help correct for spherical or chromaticaberration, or to modify or assist the collimation of image lighttowards the eye box. As an example, a design for an improved light guidetype AR headset 800 with a pin-mirror based combiner can provideaspheric or free-form lens elements that work in combination withpin-mirrors 830 that are fabricated with spatially variant tilts,widths, shapes, or curvatures.

In a design with multiple curved pin mirrors, each pin mirror cancontribute part of the imaging function of the micro-display. However,if these curved pin-mirrors don't belong to a whole large curve, thegenerated sections of the image may not be combined seamlessly anddifferent twists of the image portions can happen, meaning that theperceived image has a local or spatially variant and unintendeddistortions. One way to reduce or avoid image twist is to have eachcurved pin mirror belong to one identical or common large curved surfaceimbedded within the combiner (each pin mirror is a part of a whole largecurved mirror).

Alternate versions of an improved light guide based ARHS with imbeddedpin-mirrors 930 are shown in FIGS. 9A-E. In particular, in the versionshown in FIG. 9A, a large curved mirror 970 is provided near the bottomof the combiner or “eyepiece” 905 that can function to collimate thebeams along the horizontal plane of the eyepiece. The AR headset can beequipped with image generating optics 950 that includes an LED array 975that emits virtual image light 945, and beam shaping optics (i.e.,lenses 980) that alter the light and direct it into a light guidecombiner 905. In the exemplary embodiment that is shown, a firstcylinder lens nominally collimates the image light from pixels in theLED array 975 in the narrow (4 mm wide) direction of the light guide.FIG. 9E depicts a perspective view, showing light propagation for threefield positions. The light will reflect off an input coupling edge facet(915) and be directed into the elongate portion of the light guidecombiner 905. In this orientation, the image light will propagate inpart by TIR through the light guide 905. In the orthogonal orientation,a second cylinder lens (980) can alter the image light from beingdivergent to convergent, before the image light encounters the inputcoupling edge facet 915. A preferred configuration for this system is toprovide the LED array 975 and associated optics above the eyes, so imagelight is directed from the forehead downwards into the combiner 905.

Then, as shown in FIGS. 9A-E, a design for a visor 900 provides acombiner 905 with flat pin mirrors 930, but with a large cylindricalcurved mirror 970 near the bottom of the eyepiece/combiner 905. Once thelight has propagated through the length of the light guide combiner 905,it can hit an imbedded cylindrical curved reflector 970 and be reflectedback, and then become nominally collimated in the wide direction of thelight guide combiner 905. After collimation by the large curved mirror970 at the bottom of the combiner 905, the beams are reflected back tothe eyepiece and then can hit the array of pin mirrors 930A or 930B(collectively referred to as 930) and reflect out of the eyepiece andtowards an eye box 922 where a human eye can view a virtual image atinfinity. As an example, a light guide with a 60×50 mm size, and athickness of 4 mm, has a curvature for the large curved reflector 470 of˜30 mm, so as to modify or collimate the virtual image light for thehorizontal field of view within the eyepiece.

In the prior configuration of FIG. 7A-D, the pin-mirrors 730 were tiltedto face the incoming image light and deflect it towards the eye box 722.But in the FIG. 9A-9E configurations, the pin-mirrors 930 ormicro-mirrors can be tilted to face (e.g., at 30° the curved mirror 970,so as to re-direct light reflected from the curved mirror 970 towardsthe eye box 922. This means that during an initial transit of imagelight through the light guide combiner 905 towards the curved reflector970, some image light can encounter the “back side” of the pin-mirrors930, and be deflected outwards, towards the ambient environment, wherethis light may be noticed by other people. To reduce this effect, thepin-mirrors 930 can be fabricated with a “back side” light absorptioncoating (e.g., ≥97% light absorbing). Similar black or light absorbingcoatings can be provided on the light guide edges, including portions ofthe edge facet 915 that are not used for coupling input virtual imagelight 945 into the light guide combiner 905, so as to attenuate straylight and prevent its observance by either a viewer or people in theambient environment.

It is also noted that the curved reflector 970, rather than beingimbedded, can be provided as a mirror coating applied to a curved endface of the light guide or combiner 905. It is also noted that FIGS.9A-E depict two versions, relative to the arrangement of the pin-mirrors930 into an array. In one version (FIGS. 9A-9B), the pin-mirrors 930Aare distributed in a pin-mirror array 935A that spans most of the areaof the light guide combiner 905. In a second version (FIGS. 9C-9D), thepin-mirrors 930B are tightly clustered in a spatially variant pin-mirrorarray 935B with two adjacent groups, with a partial gap 937 betweenthem. The partial gap 937 is used prevent light loss in the centerfields and allow more light from the center field to propagate throughto the curved mirror 970 and then to pin mirrors 930.

The pin mirrors 930 are used to couple out the light reflected from thecurved reflection surface (970) in the waveguide. As an example, 2 mmwide pin-mirrors 930 tilted at 30 deg. will seem only 1 mm tall. Anoptimized pin-mirror array design can use only 20-100 pin-mirrors 930.With more pin mirrors 930 occupying a larger area, the amount of coupledout light will be larger, and thus the image brightness can increase.However, there are other trade-offs. As one example, the eye relief, orthe distance between the eye box 922 and the improved light guidecombiner 905, or eyepiece, can be reduced. The system has a finiteworking distance, as given by a distance between the curved reflector970 and its exit pupil (e.g., the location of the eye box 922). Thus,the further the pin mirrors 930 are from the curved reflector 970, thesmaller the corresponding eye relief will be. Based on this, the pinmirrors 930 cannot be too far “above” or away from the curved reflector970. Second, to expand the array area given to the pin mirrors 930, canblock more ambient light. These, and other trade-offs can be addressedduring the optimization process of the pin mirrors 930, by determiningfactors including the number, size, positions, and the ambient andvirtual image light fill factors, of the pin mirrors 930.Advantageously, this version of the improved light guide based ARHS 900with imbedded pin-mirrors 930 and curved reflector 970 can be optimizedto present virtual image light 945 to an eye box 922 over a horizontalFOV of at least 100 degrees.

In the improved light guide and pin-mirror based ARHS shown in FIGS.9A-E, the light propagates through a single light guide, to reach thecurved reflector 970, and then to reach pin-mirrors 930. Alternately,the image light could be initially coupled into a first light guide (notshown) that is nominally parallel to, but slightly offset from, by athin air gap, a second light guide having the pin-mirrors. The two lightguides merge or are contacted with an index matching material in theregion proximate to the curved reflector, so that image light can thenbe directed towards the pin-mirrors. A random arrangement of spacerbeads or posts can be used to maintain the air gap between the lightguides. While this configuration can be mechanically more complicated,virtual image light is not lost by encountering the back side of thepin-mirrors.

FIG. 10A depicts a viewer's eye receiving virtual image light from partof an AR headset having pin-mirrors. FIG. 10B depicts a viewer's eyereceiving virtual image light from part of an AR headset havingpin-mirrors. FIG. 10C depicts a viewer's eye receiving virtual imagelight from part of an AR headset having pin-mirrors. For greatercontext, FIG. 10A depicts a 3D or isometric view of a viewer's eye 1001receiving virtual image light rays 1045 from part of an improved ARheadset 1000 having pin-mirrors 1030. Image light is coupled into theplanar inner surface of the light guide combiner 1005, and reflected offof an angled edge facet towards the pin-mirrors 1030. In particular,this image depicts part of an ARHS with a curved bottom reflector ofFIG. 9A-E.

The “screen-door door” effect is normally denoted as when the fine linesseparating pixels become visible. This can be solved by increasing theresolution of the display. In the heads-mounted display, the“screen-door” effect can occur because a single display is stretched toprovide a large field of view and the fine lines between pixels becomemore visible. As the individual pin-mirrors are both small and close tothe eye, they are unlikely to cause a significant screen door effect. Ifthe pin mirrors 1030 were larger, they would need to be further awayfrom each other so as not be seen. Additionally, there is a risk ofperceptible moiré occurring. But for this light guide ARHS, as long asdifferent layers or rows of pin mirrors 1030 do not overlap with eachother, a “moiré pattern” is unlikely to occur. Also, given therelatively large size and pitch of the pin mirrors 1030 and pin mirrorarrays 1035 (mm dimensions), compared to the size of the projected imagepixels, visible moiré between the pin-mirror arrays and the imagecontent is unlikely. Additionally, the physically positioning or pitch1032 or shape of the individual pin-mirrors 1030 430 in the pin-mirrorarray or sub-arrays can be randomized to reduce the risk of perceptiblemoiré.

In general, the introduction of pin-mirrors in the combiner providesmany additional degrees of freedom for designing the visor, the imaginggenerating optics, and the AR headset. In particular, a variety ofparameters, including pin-mirror size, shape, tilt and spatial tiltvariation, gap spacing or pitch, pin-mirror or facet curvature, andoverall combiner curvature can become available.

FIG. 11 outlines an optimization method 1100 that can be used to designthe plurality of pin-mirrors, a combiner, and an AR headset generally(including the displays of FIGS. 7A-D, FIGS. 9A-E, FIGS. 10A-C, FIGS.12-13, and FIGS. 14-15). In an initial input step 1110, values or rangesfor input parameters related to the general design of the combiner andlight guide are provided, along both relevant parameters related to theimaging optics and input light coupling optics, and the parametersrelated to illuminating a viewer's eye with image light. These systemparameters (P) can include at least the target FOV, the light guide andcombiner or visor size, the light guide thickness, the eye box size andposition, and the eye relief. In a second initial input step 1120,values or ranges for parameters specific to the pin-mirrors andpin-mirror portion of the combiner are provided. These pin-mirrorparameters (P) can include the minimum pin-mirror size (to guaranteemanufacturability, and reduce image blur), the maximum pin-mirror size(to avoid pupil focus), the maximum or nominal pin-mirror spacing (toensure optical overlap), the minimum pin-mirror array size (to ensureminimum eye box size), the maximum pin-mirror array size (to fit in aneye glass lens), the pin-mirror array shape or outer contours, and thepin-mirror coating (both reflective and light absorbing) performance.Other input parameters (P) can include the length of a pre-pin-mirrorlight guide portion, the pin-mirror array fill factors (e.g., a highfill factor for the virtual image light and a low fill factor for theambient light), the facet or pin-mirror tilt, multi-plane pin mirrorarray parameters (FIG. 5A: e.g., the extent of the sub-arrays, pitchbetween sub-arrays, parallelism or relative skew or tilt between thesub-arrays, the pin-mirror positioning within the individual sub-arrays,and the avoidance of moiré), facet or pin-mirror curvature, and thespatial variation of a facet or pin-mirror tilt or curvature in either ahorizontal or vertical direction. Although the pin-mirror arrays andsub-arrays are depicted as having the pin-mirrors arranged within anominally rectangular area, the outside shape or contour of thepin-mirror arrays need not be rectangular. In particular, the pin-mirrorarray area contours can also be optimized using appropriate parametersso that the array outer edges more closely follow the edges of the eyepiece, which can be curved and shaped to better fit to the contours of aviewer's face. Using the parameters that are input in steps 1110 and1120, then initial system performance metrics can be calculated in step1130, and compared to target values.

An iterative optimization process than follows, via steps 1140 and 1145,in which values for the input parameters can be modified and newperformance values calculated and tracked. This optimization process canuse a damped least squares method, a global optimization method, orother calculative techniques. Depending on the algorithmic optimizationapproach, an additional step 1125 can be included to provide userdefined or automatic weighting values that can be used in optimizationmerit function (e.g., M=A₁P₁W₁+A₂P₂W₂+A₃P₃W₃+ . . . ). The weightingfactors (W) can be applied to both the system or pin-mirror parameters(P) and the system performance metrics (A). The optimization method 1100then nominally ends at an output step 1150, which provides “final”optimized values for the various parameters, as well system performancevalues for the performance metrics. The performance metrics determinedin steps 1130 and 1145 can include image brightness, image lightefficiency, image color or intensity uniformity, image blur or imageresolution (MTF), field of view and eye box size, and ambient lighttransmission or transparency. Of course, also, the input parameters andmerit function weightings can be changed and the method re-run.

The optimization can be separated into the optimization of projectionoptics and the optimization of the size and arrangement of the pinmirrors. Optimization or design of the projection optics can becompleted by using sequential mode in Zemax or CodeV without consideringthe out-coupling of the lightguide eyepiece (pin mirrors) and can beachieved by operating the merit function. Whereas, optimization of thesize and arrangement of the pin mirrors can be completed in designsoftware by setting each pin mirror as a detector that can detect howmuch total power is reflected to be coupled out of the lightguideeyepiece and the individual power reflected corresponding to each singlefield of light. By doing this, the relationship between the size andplacement of the pin mirrors, the total reflected power, and thereflected power for each field, can be set up and evaluated, todetermine an optimal number of pin mirrors, the pin mirror size(s), andthe pin mirror placement. In practice, in the various embodiments theoptimization of the pin-mirrors and combiner can inform or limit theoptimized design of the imaging optics, and the design of the imagingoptics can inform or limit the optimization of the pin-mirrors andcombiner. In general, the preferred fill factors can vary with the ARHSdesign and fabrication, coating properties, and the expected viewerapplications.

In the prior discussions, it is generally assumed that the visors orcombiners for the left and right eyes would have identicaloptimizations, except that for any spatial variations, one combinerwould be a mirror image of the other. However, for some applicationspecific purposes, or for a customer specific design, the visors orcombiners can be optimized differently, as can the associated imagingsystems.

FIG. 14 depicts an alternate embodiment for an improved light guidebased AR headset 1400 having a combiner 1405 with an array ofpin-mirrors 1430. In particular, FIG. 14 depicts a line scanning ARdisplay system that can be used for left eye or right eye viewing, inwhich an image source 1440 (e.g., a micro-LED array) provides imagelight 1445, via collimation and projection optics 1410, a scan mirror1420, through a lightguide or combiner 1405 having pin-mirrors 1430arranged on a plurality of pin-mirror sub-arrays 1435, to an eye 1460 atan eye box 1450. Optics 1410 can be refraction, diffraction, reflection,or electrical-controlled diffraction based, or combinations thereof. Thevisor or lightguide combiner 1405 can also be shaped and contoured toimprove the fit to a viewer's face.

It is noted that at present, it can be difficult to fabricate and sourcesmall, bright 2D micro-LED arrays 1440 with tightly packed addressableRGB image pixels (1542 see FIG. 15). As an alternative, a tri-linear RGBLED array light source can be used. For example, the LED array sourcecan be a true 1D tri-linear array that provides a line of addressableLED pixels having 1×4096 red light emitting pixels, parallel to asimilar respective rows of green light and blue light emitting pixels.Alternately, as shown in FIG. 15, the image source 1540 can be a devicethat can be described as a 2D micro-LED array or block-width tri-linearmicro-LED array. In particular, FIG. 15 depicts a portion of an LEDarray device with an arrangement of LED pixels as three linear areas orblocks such that a parallel linear array of Red (R) pixels 1542 isadjacent to a parallel linear array of Green (G) pixels 1542, that isadjacent to a parallel linear array of Blue (B) pixels 1542. Forexample, each block or linear array of pixels, whether R, G, or B, cancomprise 50×8000 pixels. The LED emitters in a given line (e.g., 50pixels wide) are individually addressed and controlled, and at any pointin time, during scanning and image display, they can be providing anintensity of image light for different details of the displayed AR imagecontent. This second approach, with a block-width tri-linear micro-LEDarray, enables embodiments of the ARHS to provide a brighter image.

Within a linear micro-LED array light source 1540, individual lightemitting pixels 1542 can also be square or rectangular in aspect ratio.As an example, an individual light emitting pixel, whether R, G, or Bcan have a nominal side dimensions of 2.5-5.0 microns width, althoughthe pixels can be smaller (e.g., 1.0 microns wide) or larger. Each blockor linear array of pixels, whether R, G, or B, can comprise 8000×50pixels. Thus, for example, with 3.2 micron square pixels, each of therespective color arrays would be 160 microns wide, and 25.6 mm long, toprovide an overall linear type device or image source 1540 that is ˜0.5mm wide and 25.6 mm long. The linear arrays of RGB image pixels 1542 inFIG. 15 can be provided with other arrangements of the colors, such R,B, G, and the number and size of image pixels need not be identical fromone color array to another. The LED array can also be equipped withmicro-optics, such as a lenslet array (not shown), to help with beamshaping. For example, a custom designed micro-lens array, aligned andmounted to collect and redirect light from the LED pixels, can havelenslets with customized shapes, or optical designs that are spatiallyvariant across the LED array or by color (R, G, B). Although FIG. 15depicts the tri-linear LED Array (1540) as a straight linear RGB device,the device can also be a white light, or monochrome or single-colordevice, or be curved (along an arc) or shaped. Curving or shaping thearray can better match an eyepiece (combiner 1505) in a way that is moreconformal to the human facial structure, and increase apparent lightefficiency to a viewer.

In either case, a tri-linear micro-LED array 1540 with LED pixels 1542can be used as an image source 1540 for the improved AR headset 1400 ofFIG. 14. The emitted image light is shaped by collimation optics (1410)and directed onto a 1D scanning micro-mirror 1420, through projectionoptics (1410), and into a combiner 1405 or eyepiece, to then transit thecombiner and be directed to the eye box. As shown, this combiner hasmultiple sub-arrays (1435) of pin-mirrors 1430. This system can providehigh brightness AR images to a viewer simultaneously along with thepresence of high brightness ambient light 1465. The 1D, 2D or customizedscanning system could be provided using a variety of mechanisms,devices, materials, or modulation components, including but not limitedto, MEMS devices, solid state displays, spatial light modulators (e.g.,back illuminated liquid crystal (LC) devices), modulation crystals, orbeam deflectors.

Operationally, the individual R, G, or B LED pixels 1542 can provideemitted light with 8-10 bits of modulation depth, at a display frequencyof 30-120 Hz, depending on the application and specifications. Both themodulation bit depth and display frequency can be increased (e.g., to12-14 bits, and 144-200 Hz, respectively) depending on the availabletechnologies and the value to the ARHS product. This modulated imagelight 1445 is then directed through optics 1410 to a linear scan mirror1420, which can be driven by a controller (not shown). The scan mirror1420 can be either a resonant or non-resonant scanner, with its scanoperation calibrated by a line scan position monitoring sensor (notshown). FIG. 14 depicts two tilt positions for this scan mirror, withopposite tilts. Scan mirror 1420 can be a MEMs (microelectromechanicalsystems) device, for example that is a single mirror with an activemirror 2.5 mm wide and 6 mm long, where the mirror tilts by ±7-10degrees about the width direction. Improved or optimized devices witheither smaller or larger (e.g., ±12°) scan angles can also be used. Theoptical scan range (angle) is 2× the mechanical scan range (angle). Thescan mirror 1420, which can also be designed as a linear array ofmultiple mirrors, can be provided by vendors such as PreciseleyMicrotechnology Corp. (Edmonton AB, CA) or Fraunhofer IPMS (Dresden,Del.). Scan mirror 1420 can also be enabled by other technologies, suchas a piezoelectric device (e.g., using PLZT) or a galvanometer. As thescan mirror 1420 tilts, the image light 1445 is swept through the lightguide combiner 1405, to reflect light off of pin-mirrors 1430, anddirect light to an eye box 1450. Image light 1445 can be provided by theLED pixels 1442, in synchronization with the scan mirror 1420 tilt, suchthat image light 1445 is directed into the eye box 1450 for an extendedduration per sweep. As image content can be provided for both directionsof scan mirror tilting, the effective operational scanning duty cyclecan be high (e.g., ˜90%).

A preferred configuration for this system is to provide the image source1440, associated optics, and scan mirror 1420, at the top, above theeyes, so image light 1445 is directed from the forehead downwards intothe combiner 1405. As previously described, a variety of pin-mirrorparameters, such as a maximum and minimum size, a pitch or gap betweenthem, and target fill factors can be defined. Then, during optimization,with an optimization method 1100 (FIG. 11), the pitch, size, shape,curvature, tilt, positioning, fill-factors, coatings, and otherparameters related the pin-mirrors 1430 and the pin-mirror sub-arrays1435, including the sub-array pitch 1432, within the combiner 1405 canbe optimized. As an example, the 1D scanning AR display system 1400 ofFIG. 14 can use an array of pin-mirrors 1430 in which the pin-mirrorshave ˜0.4-1.2 mm widths, and are spaced apart from one another by aspatially variant pitch (1432) in the ˜2-5 mm range, and combiner 1405can have a total of 300-1000 pin-mirrors 1430 distributed across one ormore imbedded pin-mirror sub-arrays 1435. But depending on the designoptimization of the pin-mirror based combiner or eye piece 1405, thenumber of pin-mirrors can be ≤50, or ≥2000, or somewhere in between. Theoptimization (e.g., FIG. 11) of the configurations of the individualpin-mirrors in the various embodiments and the pin-mirror sub-arrays inthe various embodiments, relative to pin-mirror design parameters suchas number, size, pitch, curvature, and coatings, and system parameterssuch as the target headset FOV (e.g., a WFOV ≥90° per eye), can bemotivated by many factors or performance metrics, including the lack ofvisible moiré, the apparent headset transparency for the ambient light,and the apparent brightness for display expected light. Otheroptimization or performance metrics can include factors that arespecific to a given viewer application or to the manufacturability ofthe pin-mirrors and pin-mirror arrays. The FIG. 11 pin-mirroroptimization method can also be a subset of a larger optimization methodthat includes the design of the entire combiner, or the entire ARheadset, including the design of the imaging optics, housings, andvarious light trapping or light absorbing features.

As shown in FIG. 14, the combiner 1405 used in the improved scanning andlight guide based AR headset 1400, which can be straight or curved, canbe of the type with multiple planes of parallel sub-arrays ofpin-mirrors 1430 (see also FIG. 5A and FIG. 5B). The combiner can havecurvature or shaping to help conform to the shape of a viewer's face,and curvature can be provided only outside the area used for imagedisplay, or it can extend to within the viewed area. The AR headset 1400of FIG. 14 can also be provided with pin-mirror based combiners that areof the type with a single laterally spread pin-mirror array using asingle light guide (FIG. 7(A-D)), or of the type (FIGS. 9A-E) with dualparallel light guides and a curved reflector (970) at the bottom of theeyepiece, opposite the top side image source.

The 1D scanning, pin-mirror based, AR headset 1400 of FIG. 14 also canbe advantageously adjusted for variations in interpupillary distance(IPD) amongst viewers. As an example, the device can be designed so thatnominally only 6000 pixels of an available 8000 pixels of an imagesource array (1440) are used at a given time. But the stripe of usedpixels can be selected to shift the images provided by the left eye andright eye scanning displays, to the left or right, so as to adjust fordifferent people's interpupillary distance. This capability can beenabled by a calibration set-up process or with eye tracking.

According to an alternate embodiment of the present invention, theimbedded reflector array of pin-mirrors 1230 can also be used within animproved eyepiece or reflective combiner 1205 for a projection type ARglasses display (1200), but improved over the example depicted in FIG.3A. As shown in FIG. 12, instead of having a complicated partiallyreflective coating, the inner surface 1215 of the combiner 1205 willhave an AR coating so that the virtual image light 1245 penetrates intothe combiner 1205 and interacts with pin-mirrors 1230. As shown in FIG.13, a combiner 1305 can be fabricated with a combiner substrate 1310having a plurality of pin-mirrors 1330 with a spatially varying tilt.FIGS. 12 and 13 depict a cross sectional view of a 1D row or array ofpin mirrors 1230 and 1330 respectively, arranged to provide a horizontalspatial variance of tilt alignment. More completely, a 2D array oftilted pin-mirrors 1330 is provided both horizontally and verticallyover most the height and width of a combiner lens. The combiner 1305 canbe manufactured as a flat optic (FIG. 13) using a polymer or a glassmaterial, and then slumped to conform to a curvature, or complexcurvature. Alternately, the combiner 1305 can be cast or molded with thepin-mirrors 1330 imbedded within it. Once the combiner 1305 matches thedesired shape, it can be AR coated on both the inner surface 1315 andouter surface 1320.

As another option, the combiner 1305 of FIG. 13 can also be fabricatedas a Mangin mirror. Mangin mirrors are catadioptric reflectors that aremost commonly used in telescopes or printing systems. Typically, aMangin mirror's construction consists of a concave (negative meniscus)lens made of a crown glass with spherical surfaces of different radii,and with the reflective coating on the shallower rear surface. Thespherical aberration normally produced by a simple spherical mirrorsurface is canceled out by the opposite spherical aberration produced bythe light traveling through the negative lens. In the case of the eyepiece or combiner 1205 and 1305 of FIGS. 12 and 13, the imbeddedpin-mirrors 1330 can be fabricated along a curved inner plane that has ashallower curvature than does the inner surface 1315, so as to providethe reduced spherical aberration benefits. This improvement can, inturn, ease the image quality requirements imposed on the optical designof the projection optics within the imaging systems 1340.

A completed combiner can then be used as combiner 1205 in the improvedprojection type AR glasses 1200 of FIG. 12, in which it can be used toredirect virtual image light that is incident on the combiner at theinner surface 1215, off the imbedded pin-mirrors 1230 and towards an eyebox 1250. Because of the pre-fabricated tilt variation to thepin-mirrors 1230, less curvature can be required of the combiner 1205,or less severe divergent beam angles from the imaging system 1240, orboth. Thus, the combiner and/or imaging system can be easier to designinto the glasses or provide better performance. Also, this illustratedembodiment also advantageously reduces the blur circle, as size of pinmirrors 1230 within the combiner 1205 can be sized to optimize theamount of light coming from the virtual image generators or imagingsystems 1240 and limit the local FOV of that light. This operates toreduce the blur circle and make the image more focused on the retina. Aswith the system of FIG. 3A, the imaging system 1240 can use an LED witha 2D array of light emitting pixels, and a system of beam shapingoptics.

The design of the combiner 1205, for an improved projection type ARHS,can involve parameters including the coatings, size, shape, curvature,pitch or spatial frequency, or tilt of the pin-mirrors 1230, and can beoptimized using a design process similar to that of FIG. 11, althoughthe range of tilts used for the pin-mirrors 1230 can be much greater.For example, the pin-mirrors 1230 most proximate, or across from the eyebox 1250, can be arranged nominally parallel to the inner and outersurfaces of the combiner 1205. Whereas, the pin-mirrors 1230 closer to aviewer's nose can have a local tilt relative to local curved surface ofthe combiner 1205 of only 5-10 degrees. Whereas, the pin-mirrors 1230furthest from a viewer's nose, or closest to the temples, can have alocal tilt relative to local curved surface of the combiner 705 of 15-30degrees, but of opposite orientation or sign to the pin-mirror tilt usednear the nose. Although FIGS. 12 and 13 depict combiners with spatiallyvariant pin mirror tilts in the horizontal direction, the spatialvariation can be provided in the vertical direction, or simultaneouslyin both the horizontal and vertical directions. The actual designedspatially variant angles used for the pin-mirrors depends on thedesigned radius of curvature for the combiner. This curvature is againlikely to have a complex or compound shape, but a design goal can be toreduce the radius of curvature to about half of what is was without thebenefit of the pin-mirrors while providing a WFOV. For example, themaximum radius for the compound curvature of the combiner 1205 can bereduced to ˜20-40 mm, as compared to the 60 mm referenced previously.Use of spatially variant tilt of the pin-mirrors 1230 across thecombiner also provides greater freedom to optimize the optical designproximate of the combiner or the imaging optics on the nose bridge sidedifferently than on the temple side. As another example, a design for animproved projection type AR headset 1200 with a pin-mirror basedcombiner can provide both aspheric lens elements working in combinationwith pin-mirrors 1230 fabricated with spatially variant tilts orcurvatures or shapes.

The pin-mirrors 1230 or micro-mirrors preferably have a circular orelliptical shape. Alternately, the shape or pitch or fill factor of thepin-mirrors 1230 can also vary spatially across the improved reflectivecombiner 1205. For example, near the combiner, proximate to the eye box1250, the pin-mirrors 1230 can have a spherical shape, while towards thetemples and the nose, the pin-mirrors 1230 can have an elliptical shape.The pin-mirror shape can be optimized towards satisfying a goal that theapparent pin-mirror size, as seen by a viewer, is nominally constant(e.g., within ±15% of average) across the combiner. Pin-mirrors 1230 arenominally provided with a reflectivity of 85-98%, depending on thecoating materials used, and the angle of incidence of the virtual imagelight. The pin-mirror coatings can also be dichroic notch coatings, anda spatially variant tilt of the pin-mirrors, relative to the eye-box(see FIGS. 12-13) can compensate for the dichroic coating spectralshifts that typically occur with varying incidence angle. Thepin-mirrors 1230 can also be optimized for a nominal fill factor of 50%,to allow about equal fields and amounts of ARHS image light and ambientlight to reach the eye box 1250.

Depending on the design optimization of the combiner 1205 and theoverall AR glasses 1200, the angular spread of the image ray fanprovided by an imaging system 1240, as incident to the combiner 1205,can also be eased to span a lesser angular extent than previously, allthe while at least maintaining a target WFOV of ≥90 deg. This eases theoptical design requirements imposed on the imaging systems 1240,enabling these systems to have improved performance, or smaller size, orincreased clearance for the transiting virtual image light relative to aviewer's face and head.

As an alternate example of optimization, an inner surface illuminatedARHS with a pin-mirror based combiner 1205 of the type of FIG. 12 can bedesigned with a flat or nearly flat (e.g., radius ≥200 mm) combiner,imbedded pin-mirrors, and a smaller FOV (e.g., ≤50°). As anotheralternative, an exemplary combiner can be fabricated with pin-mirrorsprovided on or near the inner surface, or on or near the outer surface.In the latter case, with the pin-mirrors proximate to the outer surface,the combiner thickness can vary spatially to provide the Mangin mirrorreduced aberration benefits. As yet another alternative, the imagingoptics can use an LED array with a 1D tri-linear array, or a veryrectangular array (aspect ratio ≥10:1) of light emitting pixels, pairedwith a linear or rectangular mirror or array of addressablemicro-mirrors to provide a virtual image light with a linear scanningconfiguration. These various projection ARHS designs using a pluralityof optimized pin-mirrors or pin-mirror arrays, can be enabled usingvariants of the optimization method of FIG. 11. By comparison to theoptimization method 1100 used for light guided ARHS previously outlinedwith respect to FIG. 11, the optimization method for the visor orcombiner for a projection type ARHS may not need all of the sameoptimization parameters or metrics, but it can need or emphasize othersinstead.

Thus, the various embodiments of the invention advantageously operate tofilter the light from the virtual images and real images. In turn, thisreduces the blur circle for both sources and results in the virtualimages and the real-world images being more in focus regardless of thedepth of the real-world elements. Thus, the foreground and thebackground elements in the real world remain in focus along with thevirtual images. The pin mirrors operate as pin holes for the light raysfrom the virtual image generators and, they also operate to createactual pin holes for the light rays from the real-world environment.Also, the optical components in these improved pin-mirror based ARHSsystems, including image source optics, projection optics, and eyepieceoptics, can include optics or components that can include, but are notlimited to, optics that are refractive, diffractive, free-form, orKinoform, Fresnel, combined elements, holographic elements, metasurfaceor sub-wavelength structured elements, gradient index elements,optomechanical components, spatial light modulators, variable shapemembranes, liquid lenses, different display components, or static orelectrical controlled crystal materials.

The present invention has been described using detailed descriptions ofembodiments thereof that are provided by way of example and are notintended to limit the scope of the invention. The described embodimentscomprise different features, not all of which are required in allembodiments of the invention. Some embodiments of the present inventionutilize only some of the features or possible combinations of thefeatures. Variations of embodiments of the present invention that aredescribed and embodiments of the present invention comprising differentcombinations of features noted in the described embodiments will occurto persons of the art.

It will be appreciated by persons skilled in the art that the presentinvention is not limited by what has been particularly shown anddescribed herein above. Rather the scope of the invention is defined bythe claims that follow.

What is claimed is:
 1. A light guided augmented reality (AR) displaycomprising: an image source; and imaging optics, wherein the imagingoptics provide an image light; a combiner into which the image light isend or edge coupled, and from which the image light is guided and outputtowards an eye box; a plurality of tilted pin-mirrors imbedded betweenan inner surface and an outer surface of the combiner, where theplurality of tilted pin-mirrors are configured to reflect the guidedimage light towards the eye box, and wherein the plurality ofpin-mirrors include one or more gaps between them wherein the one ormore gaps allow the passage of an ambient light through the combinertowards the eye box, wherein, with respect to the image light, thetilted pin-mirrors appear to form a high fill factor array, whilesimultaneously appearing as a low fill factor array for ambient lightincident to an outer side surface of the combiner, wherein the size,shape, and tilt of the pin-mirrors are optimized to reduce an imageblur.
 2. A light guided augmented reality (AR) display comprising: animage source; and imaging optics, wherein the imaging optics provide animage light; a combiner into which the image light is end or edgecoupled, and from which the image light is guided and output towards aneye box; a plurality of tilted pin-mirrors imbedded between an innersurface and an outer surface of the combiner, where the plurality oftilted pin-mirrors are configured to reflect the guided image lighttowards the eye box, and wherein the plurality of pin-mirrors includeone or more gaps between them wherein the one or more gaps allow thepassage of an ambient light through the combiner towards the eye box,wherein, with respect to the image light, the tilted pin-mirrors appearto form a high fill factor array, while simultaneously appearing as alow fill factor array for ambient light incident to an outer sidesurface of the combiner, wherein the size and spacing of the pin-mirrorsinto a two dimensional pin-mirror array is optimized to increase theoptical efficiency for directing the image light to the eye box.
 3. Alight guided augmented reality (AR) display comprising: an image source;and imaging optics, wherein the imaging optics provide an image light; acombiner into which the image light is end or edge coupled, and fromwhich the image light is guided and output towards an eye box; aplurality of tilted pin-mirrors imbedded between an inner surface and anouter surface of the combiner, where the plurality of tilted pin-mirrorsare configured to reflect the guided image light towards the eye box,and wherein the plurality of pin-mirrors include one or more gapsbetween them wherein the one or more gaps allow the passage of anambient light through the combiner towards the eye box, wherein, withrespect to the image light, the tilted pin-mirrors appear to form a highfill factor array, while simultaneously appearing as a low fill factorarray for ambient light incident to an outer side surface of thecombiner, wherein the gaps between rows of the pin-mirrors are arrangedinto a two dimensional pin-mirror array, and the gap widths areoptimized to increase the optical efficiency for the transmission ofambient light towards the eye box.
 4. A light guided augmented reality(AR) display comprising: an image source; and imaging optics, whereinthe imaging optics provide an image light; a combiner into which theimage light is end or edge coupled, and from which the image light isguided and output towards an eye box; a plurality of tilted pin-mirrorsimbedded between an inner surface and an outer surface of the combiner,where the plurality of tilted pin-mirrors are configured to reflect theguided image light towards the eye box, and wherein the plurality ofpin-mirrors include one or more gaps between them wherein the one ormore gaps allow the passage of an ambient light through the combinertowards the eye box, wherein, with respect to the image light, thetilted pin-mirrors appear to form a high fill factor array, whilesimultaneously appearing as a low fill factor array for ambient lightincident to an outer side surface of the combiner, wherein the tilts ofthe pin-mirrors, relative to the inner and outer surfaces of thecombiner vary spatially across the combiner.
 5. A light guided augmentedreality (AR) display comprising: an image source; and imaging optics,wherein the imaging optics provide an image light; a combiner into whichthe image light is end or edge coupled, and from which the image lightis guided and output towards an eye box; a plurality of tiltedpin-mirrors imbedded between an inner surface and an outer surface ofthe combiner, where the plurality of tilted pin-mirrors are configuredto reflect the guided image light towards the eye box, and wherein theplurality of pin-mirrors include one or more gaps between them whereinthe one or more gaps allow the passage of an ambient light through thecombiner towards the eye box, wherein, with respect to the image light,the tilted pin-mirrors appear to form a high fill factor array, whilesimultaneously appearing as a low fill factor array for ambient lightincident to an outer side surface of the combiner, wherein the size orshape of the pin-mirrors and the gaps between them, are spatiallyvariant across the combiner.
 6. A light guided augmented reality (AR)display comprising: an image source; and imaging optics, wherein theimaging optics provide an image light; a combiner into which the imagelight is end or edge coupled, and from which the image light is guidedand output towards an eye box; a plurality of tilted pin-mirrorsimbedded between an inner surface and an outer surface of the combiner,where the plurality of tilted pin-mirrors are configured to reflect theguided image light towards the eye box, and wherein the plurality ofpin-mirrors include one or more gaps between them wherein the one ormore gaps allow the passage of an ambient light through the combinertowards the eye box, wherein, with respect to the image light, thetilted pin-mirrors appear to form a high fill factor array, whilesimultaneously appearing as a low fill factor array for ambient lightincident to an outer side surface of the combiner, wherein the pluralityof pin-mirrors is provided as multiple sub-arrays of pin-mirrors, eachprovided on an imbedded surface within the combiner relative to theinner and outer surfaces of the combiner, wherein the arrangement ofpin-mirrors or pin-mirror sub-arrays varies spatially across thecombiner.
 7. A light guided augmented reality (AR) display comprising:an image source; and imaging optics, wherein the imaging optics providean image light; a combiner into which the image light is end or edgecoupled, and from which the image light is guided and output towards aneye box; a plurality of tilted pin-mirrors imbedded between an innersurface and an outer surface of the combiner, where the plurality oftilted pin-mirrors are configured to reflect the guided image lighttowards the eye box, and wherein the plurality of pin-mirrors includeone or more gaps between them wherein the one or more gaps allow thepassage of an ambient light through the combiner towards the eye box,wherein, with respect to the image light, the tilted pin-mirrors appearto form a high fill factor array, while simultaneously appearing as alow fill factor array for ambient light incident to an outer sidesurface of the combiner, wherein the plurality of pin-mirrors isprovided as multiple sub-arrays of pin-mirrors, each provided on animbedded surface within the combiner relative to the inner and outersurfaces of the combiner, wherein at least one sub-array of pin-mirrorsis formed onto an internal curved surface.
 8. A light guided augmentedreality (AR) display comprising: an image source; and imaging optics,wherein the imaging optics provide an image light; a combiner into whichthe image light is end or edge coupled, and from which the image lightis guided and output towards an eye box; a plurality of tiltedpin-mirrors imbedded between an inner surface and an outer surface ofthe combiner, where the plurality of tilted pin-mirrors are configuredto reflect the guided image light towards the eye box, and wherein theplurality of pin-mirrors include one or more gaps between them whereinthe one or more gaps allow the passage of an ambient light through thecombiner towards the eye box, wherein, with respect to the image light,the tilted pin-mirrors appear to form a high fill factor array, whilesimultaneously appearing as a low fill factor array for ambient lightincident to an outer side surface of the combiner, wherein the imagesource includes a tri-linear pixelated light emitting array and ascanning mirror device, wherein the arrangement of pin-mirrors orpin-mirror sub-arrays varies spatially across the combiner.
 9. A lightguided augmented reality (AR) display comprising: an image source; andimaging optics, wherein the imaging optics provide an image light; acombiner into which the image light is end or edge coupled, and fromwhich the image light is guided and output towards an eye box; aplurality of tilted pin-mirrors imbedded between an inner surface and anouter surface of the combiner, where the plurality of tilted pin-mirrorsare configured to reflect the guided image light towards the eye box,and wherein the plurality of pin-mirrors include one or more gapsbetween them wherein the one or more gaps allow the passage of anambient light through the combiner towards the eye box, wherein, withrespect to the image light, the tilted pin-mirrors appear to form a highfill factor array, while simultaneously appearing as a low fill factorarray for ambient light incident to an outer side surface of thecombiner, wherein the image source includes a tri-linear pixelated lightemitting array and a scanning mirror device, wherein the arrangements ofthe plurality of pin-mirrors within a pin-mirror sub-array is differentfor at least two sub-arrays.
 10. A light guided augmented reality (AR)display comprising: an image source; and imaging optics, wherein theimaging optics provide an image light; a combiner into which the imagelight is end or edge coupled, and from which the image light is guidedand output towards an eye box; a plurality of tilted pin-mirrorsimbedded between an inner surface and an outer surface of the combiner,where the plurality of tilted pin-mirrors are configured to reflect theguided image light towards the eye box, and wherein the plurality ofpin-mirrors include one or more gaps between them wherein the one ormore gaps allow the passage of an ambient light through the combinertowards the eye box, wherein, with respect to the image light, thetilted pin-mirrors appear to form a high fill factor array, whilesimultaneously appearing as a low fill factor array for ambient lightincident to an outer side surface of the combiner, wherein the imagesource includes a tri-linear pixelated light emitting array and ascanning mirror device wherein the image light is coupled into a firstlight guide to transit the first light guide and reflect off of a curvedreflector to enter a second light guide where the image light interactswith the plurality of pin-mirrors.
 11. A light guided augmented reality(AR) display comprising: an image source; and imaging optics, whereinthe imaging optics provide an image light; a combiner into which theimage light is end or edge coupled, and from which the image light isguided and output towards an eye box; a plurality of tilted pin-mirrorsimbedded between an inner surface and an outer surface of the combiner,where the plurality of tilted pin-mirrors are configured to reflect theguided image light towards the eye box, and wherein the plurality ofpin-mirrors include one or more gaps between them wherein the one ormore gaps allow the passage of an ambient light through the combinertowards the eye box, wherein, with respect to the image light, thetilted pin-mirrors appear to form a high fill factor array, whilesimultaneously appearing as a low fill factor array for ambient lightincident to an outer side surface of the combiner, wherein the imagelight is coupled into a first light guide, to transit the first lightguide, and reflect off of a curved reflector, to enter a second lightguide where the image light interacts with the plurality of pin-mirrors.